In the initial periods of human civilization, the world population was very less. Around 8000 to 12000 years before, after the evolution and beginning of agriculture, the size of population was very small. In around 10000 BCE, the entire world population was around 50 lakh. In 150 CE, world population increased to 25 crore.
In 1650, world population increased to 50 crore. From the above mentioned facts, it is clear that in 150 CE, world population was 25 crore, and it took a period of 1500 years to double upto 50 crore. In 1850, population increased to 100 crore and it took only 200 years to double up. After this, decline is being witnessed at a rapid rate in the period in which the population in the world is getting doubled.
In 1930, world population was 200 crores which doubled up in 80 years, and which, after 45 years, again doubled to 400 crore in 1975. Keeping in view the population increase rates of the present time, it was expected that the 400 crore population of 1975 will take a time of around 37 years to double up to 800 crore, but this belief proved to be wrong. At present, the world population has reached upto 720 crore (according to 2015 data).
